US5457264A - Method of melting treatment of radioactive miscellaneous solid wastes - Google Patents

Method of melting treatment of radioactive miscellaneous solid wastes Download PDF

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Publication number
US5457264A
US5457264A US08/288,602 US28860294A US5457264A US 5457264 A US5457264 A US 5457264A US 28860294 A US28860294 A US 28860294A US 5457264 A US5457264 A US 5457264A
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United States
Prior art keywords
solid wastes
miscellaneous solid
melting
melting furnace
radioactive
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US08/288,602
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English (en)
Inventor
Hiroaki Kobayashi
Jin Ohuchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Doryokuro Kakunenryo Kaihatsu Jigyodan
Japan Atomic Energy Agency
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Doryokuro Kakunenryo Kaihatsu Jigyodan
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Assigned to DORYOKURO KAKUNENRYO KAIHATSU JIGYODAN reassignment DORYOKURO KAKUNENRYO KAIHATSU JIGYODAN ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KOBAYASHI, HIROAKI, OHUCHI, JIN
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Assigned to JAPAN NUCLEAR CYCLE DEVELOPMENT INSTITUTE reassignment JAPAN NUCLEAR CYCLE DEVELOPMENT INSTITUTE CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: JIGYODAN, DORYOKURO KAKUNENRYO KAIHATSU
Assigned to JAPAN ATOMIC ENERGY AGENCY, INDEPENDENT ADMINISTRATIVE CORPORATION reassignment JAPAN ATOMIC ENERGY AGENCY, INDEPENDENT ADMINISTRATIVE CORPORATION CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: JAPAN NUCLEAR CYCLE DEVELOPMENT INSTITUTE
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/28—Treating solids
    • G21F9/30—Processing
    • G21F9/308—Processing by melting the waste
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/02—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture in electric furnaces, e.g. by dielectric heating
    • C03B5/021—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture in electric furnaces, e.g. by dielectric heating by induction heating
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/28—Treating solids
    • G21F9/30—Processing
    • G21F9/301—Processing by fixation in stable solid media
    • G21F9/302—Processing by fixation in stable solid media in an inorganic matrix
    • G21F9/305—Glass or glass like matrix
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2211/00—Heating processes for glass melting in glass melting furnaces
    • C03B2211/70—Skull melting, i.e. melting or refining in cooled wall crucibles or within solidified glass crust, e.g. in continuous walled vessels
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping

Definitions

  • the present invention relates to a method of collective melting treatment of radioactive miscellaneous solid wastes, without classifying them, by using a cold crucible induction melting process, and more specifically, to a method capable of collectively reducing the volume of and solidifying various kinds of radioactive solid wastes, such as inflammables, metals, glasses and other nonflammables.
  • Nuclear facilities or the like produce large amounts of radioactive miscellaneous solid wastes which contain in mixed form various kinds of substances, such as inflammables, metals, glasses and other nonflammables. Since such radioactive miscellaneous solid wastes have different radioactive levels or mixture ratios among various wastes-producing facilities, it is impossible to generally compare the radioactive miscellaneous solid wastes. However, in high-level solid wastes generated from reprocessing facilities, various substances are mixed, such as metals, woods, rags, etc. Although the mixture ratio differs with each operational condition, it is reasonably estimated that metals account for about 90% and the remainder consists of inflammables (rags or the like) and nonflammables (plastic sheets or the like).
  • a conventionally proposed method of melting treatment is a high-temperature melting method such as plasma melting.
  • molten matter makes direct contact with constituent materials of a melting furnace, e.g. refractory materials of furnace-wall or electrodes, under melting temperature conditions for a substance to be melted. Accordingly, a counter-measure against high-temperature erosion (allowance for erosion or replacement of constituent materials) and the limitation of a melting temperature (the upper limit is the temperature below which the strength of constituent materials can be assured) become great problems. Specifically, the life of the constituent materials is short owing to severe high-temperature erosion, and large amounts of secondary wastes are generated as a result of the replacement of eroded constituent materials. In addition, since the melting temperature is limited, it is difficult to effect melting treatment of high melting-point metals.
  • An object of the present invention is to solve the above-described problems of the prior art and to provide a method of melting treatment of radioactive miscellaneous solid wastes which can simultaneously solve the problem of high-temperature erosion and damage sustained by the constituent materials of the melting furnace and the problem of the limitation of a melting operation temperature set by the heat-resistance temperature of the constituent materials of the melting furnace.
  • a method of melting treatment of radioactive miscellaneous solid wastes containing therein an electrically conductive substance and other waste components comprising: charging the radioactive miscellaneous solid wastes into a cold crucible induction melting furnace provided with a high-frequency coil; supplying a high-frequency current to the high-frequency coil of the melting furnace to thereby heat and melt the electrically conductive substance in the miscellaneous solid wastes; indirectly heating the other components in the miscellaneous solid wastes by utilizing the electrically conductive substance as a starting source of heating and melting; and placing the whole of the radio-active miscellaneous solid wastes into a molten state.
  • the molten matter is made to flow into a container, such as a canister, and cooled to form waste solidified matter. Also, after placing the whole of the radioactive miscellaneous solid wastes into the molten state by the aforesaid method, it is also possible to separate the respective molten waste components in the melting furnace on the basis of the difference in specific gravity among the molten waste components and cause the molten waste components to flow into individual canisters or the like by an overflow system or a bottom flow system so that the respective molten waste components can be separately discharged from the melting furnace.
  • metals contained in the radioactive miscellaneous solid wastes charged into the cold crucible induction melting furnace have electrical conductivity, when a high-frequency current is supplied to the high-frequency coil, the metals are induction-heated and melted by electricity flowing in the metals. That is to say, the metals become the starting source of heating and melting. Inflammables which surround the metals and nonflammables such as glass are indirectly heated by the heat generated from the metals. The inflammables contained in the radioactive miscellaneous solid wastes burn and reduce in volume, while the nonflammables melt. When glass substances are melted, they exhibit electrical conductivity, so that current flows in the molten glass in response to the high-frequency current of the high-frequency coil and the molten glass are directly heated. In this manner, the molten state gradually expands until the whole of the radioactive miscellaneous solid wastes reaches a molten state.
  • the molten metal Since a floating force works on the molten metal itself by the action of an electromagnetic field, the molten metal does not make direct contact with the inner wall of the melting furnace. Since the surface of the molten glass which is in contact with the inner wall of the melting furnace becomes a solid layer (skull), the molten matter do not make direct contact with a furnace material. Thus, it is possible to prevent high-temperature erosion of the melting furnace. Also, since the melting furnace itself is water-cooled, the melting temperature of the miscellaneous solid wastes is not limited by the heat-resistance temperature of the melting furnace. Accordingly, it is possible to perform melting treatment of radioactive miscellaneous solid wastes at arbitrary temperatures by the supply of the required electrical power.
  • FIG. 1 is an explanatory view showing an example of a cold crucible induction melting furnace used in the present invention.
  • FIG. 1 is an explanatory view showing an example of an apparatus for carrying out the method of the present invention.
  • a cold crucible induction melting furnace 10 has a construction in which a slit-divided water-cooled type of melting furnace 12 made of copper is installed in a water-cooled type of high-frequency coil 14. Radioactive miscellaneous solid wastes 16 are charged into the melting furnace 12. Then, cooling water 20 is circulated to cool the apparatus, and a high-frequency current is supplied to the high-frequency coil 14 from a high-frequency power source 22.
  • the metals in the radioactive miscellaneous solid wastes are heated, and substances which surround the metals are indirectly heated by the heat generated from the metals.
  • the inflammables contained in the radioactive miscellaneous solid wastes burn.
  • the radioactive substances contained in the gases produced during the combustion are captured in an off-gas system (not shown).
  • the other nonflammables are placed in a molten state.
  • glass substances are directly heated since they exhibit electrical conductivity when they are melted. Accordingly, the molten state is expanded by continuing to supply the current to the high-frequency coil 14, and the whole of the inside of the melting furnace is filled with molten matter 18.
  • the molten metal does not make direct contact with the inner wall of melting furnace 12. Since the surface of the molten glass which is in contact with the inner wall of the melting furnace 12 becomes a solid layer (skull), the molten matter 18 does not make direct contact with a furnace material. Thus, it is possible to prevent high-temperature erosion of the melting furnace. Also, since the melting furnace 12 itself is water-cooled, the melting temperature of the miscellaneous solid wastes is not limited by the heat-resistance temperature of the melting furnace. Accordingly, it is possible to perform melting treatment of radioactive miscellaneous solid wastes at arbitrary temperatures by the supply of the required electrical power.
  • the molten matter subjected to the melting treatment in the above-described manner is then injected into a canister (a container made of stainless steel) to form solidified waste matter 24.
  • a canister a container made of stainless steel
  • solidified waste matter 24 After the whole of the inside of the melting furnace 12 has been put into the molten state, it is also possible to separate the respective molten waste components on the basis of the differences in specific gravity among them and separately discharged the respective wastes from the melting furnace by an overflow system or a bottom flow system.
  • the construction of a melting furnace employed in this example is similar to that shown in FIG. 1.
  • the melting furnace employed had a structure of internal diameter of 50 mm ⁇ and a depth of 80 mm which was divided into ten segments.
  • the high-frequency coil was an 8-turn double coil having an outer diameter of approximately 190 mm ⁇ and a height of approximately 100 mm.
  • the high-frequency power source frequency of the supplied electrical power was 300 kHz.
  • a mixture of stainless steel chips 50 g and glass beads 50 g was employed as the simulated miscellaneous solid wastes, and induction heating was performed under the above-described testing conditions.
  • the size of the stainless steel chips was a square of 10 mm ⁇ 10 mm having a thickness of 1 mm.
  • the composition of the glass beads employed was as shown in Table 1.
  • the stainless steel chips When a high-frequency current was made to conduct through the high-frequency coil, the stainless steel chips first melted as the starting source of direct heating, and the surrounding glass beads melted by the heat source of the molten steel.
  • the melting temperature was approximately 1,500° C. After the melting temperature was held for approximately 30 minutes, the molten waste was cooled. After cooled the solidified matter was taken out from the melting furnace and cut into pieces, and the cut pieces were observed.
  • the testing conditions used in the above-described embodiment for example, the number of turns of the heating coil, the number of segments (slits) of the melting furnace and the power source frequency, are selected to be optimum values for the size of the melting furnace, an object to be melted and the like. Needless to say, the present invention is not limited to the aforesaid values.
  • the present invention employs the cold crucible induction melting technique as described above, the constituent materials of the furnace do not make direct contact with the molten matter which is in a molten state, no high-temperature erosion of the constituent materials occurs. Accordingly, the life of the melting furnace is improved, and the amount of occurrence of secondary wastes can be decreased.
  • the heat-resistance temperature of the constituent materials of the furnace is the upper limit of the furnace operation temperature.
  • the molten matter itself is induction-heated and the constituent materials of the furnace are water-cooled, so that this temperature limitation is eliminated. Accordingly, it is possible to perform melting treatment of radioactive miscellaneous solid wastes which contain high melting-point substances such as metals.
  • the radioactive miscellaneous solid wastes since part (metals) in the radioactive miscellaneous solid wastes become the starting source of heating and melting, it is possible to collectively perform melting treatment of nonclassified radioactive miscellaneous solid wastes which contain electrically nonconductive materials.
  • the overflow system or the bottom flow system which utilizes the differences in specific gravity among the molten waste components are adopted to charge the molten matter into a canister or the like, whereby separation of the respective waste components can be easily performed.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • Gasification And Melting Of Waste (AREA)
  • Processing Of Solid Wastes (AREA)
US08/288,602 1993-08-25 1994-08-10 Method of melting treatment of radioactive miscellaneous solid wastes Expired - Lifetime US5457264A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP5232380A JP2767189B2 (ja) 1993-08-25 1993-08-25 放射性雑固体廃棄物の溶融処理方法
JP5-232380 1993-08-25

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US5457264A true US5457264A (en) 1995-10-10

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US (1) US5457264A (ja)
EP (1) EP0640992B1 (ja)
JP (1) JP2767189B2 (ja)
DE (1) DE69403409T2 (ja)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5901169A (en) * 1997-01-09 1999-05-04 Japan Nuclear Cycle Development Institute Apparatus for discharging molten matter from cold crucible induction melting furnace
US6476285B1 (en) 1996-11-22 2002-11-05 Japan Nuclear Cycle Development Institute Method of melting treatment of radioactive miscellaneous solid wastes
JP2014132249A (ja) * 2013-01-07 2014-07-17 National Institute For Materials Science セシウム抽出法
US11570856B2 (en) * 2017-07-03 2023-01-31 Denki Kogyo Company, Limited Induction heating device, radioactive waste melting process device equipped with said induction heating device, and radioactive waste melting and solidification process device

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2989555B2 (ja) * 1996-11-22 1999-12-13 核燃料サイクル開発機構 放射性固体廃棄物の溶融処理方法
JP3463931B2 (ja) * 2001-05-25 2003-11-05 核燃料サイクル開発機構 使用済核燃料の乾式再処理法及び乾式再処理法に用いる誘導加熱装置。
KR100508129B1 (ko) * 2002-08-30 2005-08-19 한국수력원자력 주식회사 플라즈마 용융시스템의 폐기물 투입, 배기가스 배출장치및 그 시스템을 이용한 폐기물 처리방법
KR101636979B1 (ko) 2015-12-16 2016-07-07 뉴클리어솔루션 주식회사 플라즈마 토치 조립체 및 이를 갖는 폐기물 용융설비

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4049384A (en) * 1975-04-14 1977-09-20 Arthur D. Little, Inc. Cold crucible system
US4341915A (en) * 1979-03-13 1982-07-27 Daidotokushuko Kabushikikaisha Apparatus for filling of container with radioactive solid wastes
US4402724A (en) * 1978-09-29 1983-09-06 Kernforschungszentrum Karlsruhe Gmbh Method and apparatus for discharging glass from a melting furnace
US4591454A (en) * 1981-04-14 1986-05-27 Doryokuro Kakunenryo Kaihatsu Jigyodan Apparatus and method for melting and treating metal wastes
US4666490A (en) * 1986-02-12 1987-05-19 Drake Ronald N Aqueous waste vitrification process and apparatus
US4816228A (en) * 1985-03-14 1989-03-28 Ngk Insulators, Ltd. Apparatus for melting waste
US5082603A (en) * 1990-03-15 1992-01-21 Doryokuro Kakunenryo Kaihatsu Jigyodan Method of treatment of high-level radioactive waste
US5127941A (en) * 1989-06-22 1992-07-07 Jeumont-Schneider Process and device for separating the constituents of an alloy
US5185104A (en) * 1989-01-28 1993-02-09 Doryokuro Kakunenryo Kaihatsu Jigyodan Method of treatment of high-level radioactive waste
US5367532A (en) * 1991-03-05 1994-11-22 Commissariat A L'energie Atomique Furnace for the continuous melting of oxide mixtures by direct induction with high frequency, a very short refining time and a low energy consumption

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JPS6019478B2 (ja) * 1978-07-06 1985-05-16 株式会社 東芝 放射性廃棄物のガラス固化法及びガラス固化装置
JPS6114597A (ja) * 1984-06-29 1986-01-22 日本碍子株式会社 放射性廃棄物の溶融固化方法および装置
JPS6227699A (ja) * 1985-07-29 1987-02-05 株式会社東芝 放射性廃棄物中間貯蔵体の製造方法
JPH077102B2 (ja) * 1988-10-21 1995-01-30 動力炉・核燃料開発事業団 廃棄物処理用溶融炉及びその加熱方法
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4049384A (en) * 1975-04-14 1977-09-20 Arthur D. Little, Inc. Cold crucible system
US4402724A (en) * 1978-09-29 1983-09-06 Kernforschungszentrum Karlsruhe Gmbh Method and apparatus for discharging glass from a melting furnace
US4341915A (en) * 1979-03-13 1982-07-27 Daidotokushuko Kabushikikaisha Apparatus for filling of container with radioactive solid wastes
US4591454A (en) * 1981-04-14 1986-05-27 Doryokuro Kakunenryo Kaihatsu Jigyodan Apparatus and method for melting and treating metal wastes
US4816228A (en) * 1985-03-14 1989-03-28 Ngk Insulators, Ltd. Apparatus for melting waste
US4666490A (en) * 1986-02-12 1987-05-19 Drake Ronald N Aqueous waste vitrification process and apparatus
US5185104A (en) * 1989-01-28 1993-02-09 Doryokuro Kakunenryo Kaihatsu Jigyodan Method of treatment of high-level radioactive waste
US5127941A (en) * 1989-06-22 1992-07-07 Jeumont-Schneider Process and device for separating the constituents of an alloy
US5082603A (en) * 1990-03-15 1992-01-21 Doryokuro Kakunenryo Kaihatsu Jigyodan Method of treatment of high-level radioactive waste
US5367532A (en) * 1991-03-05 1994-11-22 Commissariat A L'energie Atomique Furnace for the continuous melting of oxide mixtures by direct induction with high frequency, a very short refining time and a low energy consumption

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International Conference on Nuclear Fuel Reprocessing and Waste Management Recod, Aug. 23-27, 1987, pp. 723-729.

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6476285B1 (en) 1996-11-22 2002-11-05 Japan Nuclear Cycle Development Institute Method of melting treatment of radioactive miscellaneous solid wastes
US5901169A (en) * 1997-01-09 1999-05-04 Japan Nuclear Cycle Development Institute Apparatus for discharging molten matter from cold crucible induction melting furnace
JP2014132249A (ja) * 2013-01-07 2014-07-17 National Institute For Materials Science セシウム抽出法
US11570856B2 (en) * 2017-07-03 2023-01-31 Denki Kogyo Company, Limited Induction heating device, radioactive waste melting process device equipped with said induction heating device, and radioactive waste melting and solidification process device

Also Published As

Publication number Publication date
DE69403409T2 (de) 1997-09-18
JP2767189B2 (ja) 1998-06-18
EP0640992A1 (en) 1995-03-01
DE69403409D1 (de) 1997-07-03
EP0640992B1 (en) 1997-05-28
JPH0763895A (ja) 1995-03-10

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